1. Field of the Invention
The present invention relates to electronic semiconductor devices, and, more particularly, to monolithic microwave and millimeter wave devices and systems.
2. Description of the Related Art
Microwave and millimeter wave transmitters are usually designed around discrete components. A transmitter requires a power source (free-running or controlled oscillator) and a radiating element (antenna); however, the technologies typically used to fabricate the oscillator and the antenna are incompatible. Thus hybrid transmitters with the oscillator and the antenna on separate substrates is standard. Monolithic millimeter wave oscillators often use IMPATT diodes with the frequency of oscillation determined by circuit impedance and specific diode conditions or by injection-locking signals; and the oscillator power is typically coupled out by a microstrip transmission line and fed into a microstrip patch or waveguide antenna. See for example R. Dinger et al, A 10 GHz Space Power Combiner with Parasitic Injection Locking, 1986 IEEE MTT Symposium Digest 163 and K. Carver et al, Microstrip Antenna Technology, 29 IEEE Tr.Ant.Prop. 2 (1981). For a transmitter operating over a band of frequencies, the antenna and the oscillator are designed for close impedance match throughout the bandwidth of operation to minimize mismatch losses.
However, the known transmitters have the problems of mismatch losses, design difficulties, and hybrid fabrication cost and difficulties.
Further, a hybrid transmitter precludes the possibility of monolithic integration of the transmitter with other devices such as mixers, detectors, capacitors, and transistors.